Ok, that looks good. I would guess that you'll need to swap and/or flip one or two of the channels in your normal map for it to work like it should. Unfortunately I don't know which ones or how and I don't have time to test it out right now myself.

I tested some things with it and had to ask the rest of the team because I couldn't get it to work either. Apparently it's no longer the "cubemapitem" shader you should use if you want to use a tangent space normal map on an item, but simply the "cubemap" shader.